Laser welded step motor construction with compact end cap and stator lamination positioning

Abstract

The method of providing a motor, includes providing a first thin-walled end cap having first inner and outer walls connected by a first integral side wall, the first outer wall defining a first terminal edge; providing a second thin-walled end cap having second inner and outer walls connected by a second integral side wall, the second outer wall defining a second terminal edge; providing a stator, having multiple parallel laminations defining an axially extending bore to receive a laminated rotor, the stator having end laminations, positioning the end caps so that the edges extend adjacent stator opposite end laminations.

1. A method for making motor assembly, comprising steps of:
 a) providing a first thin-walled end cap having first inner and outer walls connected by a first integral side wall, the first outer wall defining a first terminal edge, 
 b) providing a second thin-walled end cap having second inner and outer walls connected by a second integral side wall, the second outer wall defining a second terminal edge, 
 c) providing a stator, having multiple parallel laminations defining an axially extending bore to receive a laminated rotor on a rotatable shaft, said stator having axially spaced end laminations, 
 d) positioning said first and second end caps at opposite ends of the stator so that said first edge extends adjacent one of the stator end laminations and the second edge extends adjacent another of said stator end laminations at the opposite end of the stator, 
 e) and locally laser welding said edges to said stator end laminations, only at spaced locations about said axis and at the peripheries of said end laminations. 
 
   
   
     2. The method of  claim 1  including providing a first bearing unit having annular inner and outer races, and axially installing said outer race in interference engagement with the inner thin wall of one of said first end caps, and to flex said inner wall proximate said terminal edge thereof projecting away from said first cap side wall, thereby providing first cap positive frictional retention to the first bearing unit. 
   
   
     3. The method of  claim 2  including providing a second bearing unit having inner and outer races, and installing said outer race in radially spaced relation to the inner thin wall of said second end cap, and providing and installing a spacer sleeve between and in interference engagement with said second bearing outer race and with said second cap inner thin wall, to flex said inner thin wall proximate said terminal edge thereof projecting away from said second cap side wall, thereby providing second cap positive frictional retention to the second bearing unit. 
   
   
     4. The method of  claim 2  wherein the first end cap inner wall has an edge, and including locating said edge proximate a corner of the stator and proximate a corner of rotor laminations, and also proximate a corner of the first bearing outer race. 
   
   
     5. The method of  claim 1  wherein said end cap terminal edges are peripherally laser welded to stator end laminations in parallel planes at opposite ends of the stator. 
   
   
     6. The method of  claim 5  wherein said end caps are formed and positioned to have said terminal edges brought into abutting relation to flat end faces of stator end laminations for accurate laser welding thereto. 
   
   
     7. The method of  claim 6  including effecting said laser welding only at spaced apart locations about said axis and at local positions along said edges. 
   
   
     8. The method of  claim 1  including mounting an insert or inserts on an end wall defined by one of the end caps. 
   
   
     9. The method of  claim 1  wherein said end caps are provided to have differential inner wall diameters, and said bearing units have the same outer diameters, said end cap inner wall terminal edges flexed toward said outer wall terminal edges. 
   
   
     10. The method of  claim 1  including providing and positioning a magnet element between rotor laminations, about half way along the rotor laminations overall length, to include magnetic flux generation. 
   
   
     11. The method of  claim 1  including pre-assembling the first bearing to the first end cap, and subsequently effecting laser welding of the first end cap to stator end lamination or laminations, at spaced locations about said axis.